The use of certain types of ablative layers on surfaces is known for the purpose of dissipating electrical lightning strikes and for heat dissipation. In spacecraft design, ablation is used to both cool and protect mechanical parts that would otherwise be damaged by extremely high temperatures. For example, ablative layers on structures such as heat shields and rocket engine nozzles are designed to detach from a surface for the purpose of directing heat away from a surface exposed to heat stress. In such uses, the ablative surface is exposed to significant heat. When a critical temperature is reached, the reactive ablative material reaches its sublimation temperature and “explodes” away from the surface. In essence, ablative material is therefore designed to slowly burn away in a controlled manner, so that heat can be carried away (and therefore dissipated from the spacecraft surface) by the gases generated by the ablative process, while the remaining solid material insulates the craft from superheated gases.
Material ablation at high power densities is a complex combination of processes. To protect the underlying structure, ablative materials have been selected to be thermal insulators. However, known ablative materials have experienced localized heat deposition on the surface that builds up faster than the heat can be directed away from the surface. As a result, the surface temperature rises rapidly and leads to thermal degradation of the surface. Organic components then vaporize, leaving behind a charred surface. This can lead to the melting or vaporizing of underlying structural layers and fibers that become exposed. Further, pockets of hot gas may lead to micro-explosions, fracturing and rapid failure.